Lock



y 1934- J. w. FITZ GERALD ,960,263

LOCK

Filed Jan. 19, 1933 2 Sheets-Sheet 1 8 v 7 QMUMQ L/Zvhri Mfi/fZEF/F/i E S l May 29, 1934- J. w. FlTZ GERALD QMw/MM Jam WE/ZEEPE/d st A. g

Patented May 29, 1934 UNETED srAr-ss rnrsnr orrics LOCK Application January 19, 1933, Serial No. 652,453

5 Claims.

This invention relates to certain new and useful improvements in tumbler locks and has as a general object to provide a lock which cannot be decoded.

Heretofore, tumbler locks of the type having plate tumblers movable transversely to the axis of the rotatable plug or cylinder have been open to the objection that with the proper instrumentalities, the exact combination could be deciphered or decoded, thus permitting a key to be cut to fit the particular lock. In decoding a look, a feeling instrument is inserted into the key slot to measure the different locations of the key engaging portions on the tumblers with respect to a known surface. After these diiferent locations are ascertained, it is a simple matter to lay out the contour of the key and out a key blank accordingly.

However, decoding of a lock requires a known or fixed surface to measure from. Where each tumbler is one of a few definite series, definite as to the location of the key openings with re spect to the operative ends of the tumblers, decoding is a simple matter. locks wherein the tumblers are cut to size after assembly and with the proper key in place, decoding is more diiiicult, but can be accomplished by using the bottom of the tumbler groove as the fixed surface from which to measure the difierent key engaging portions.

It is this particular disadvantage of tumbler plate locks of the character described which this invention is intended to overcome, and, it is, therefore, a specific object of this invention to provide a lock in which the bottom of the tumbler groove is uneven.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangements of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

In the accompanying drawings, several complete examples of the physical embodiment of this invention are illustrated constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a View of a conventional lock cylinder with parts broken away and in section and illustrating the tumblers in their free extended positions;

Figure 2 is a longitudinal section view in perspective through a lock casing illustrating the novel formation of the tumbler receiving groove;

Figure 3 is an enlarged section view through the assembled lock casing and cylinder;

Figure i is a view similar to figure 2 illustrating a modification of this invention; and

Figure 5 is a section view taken through Figure 4 on the plane of the line 5-5.

springs 8 confined between shoulders on the tumblers (not shown) and suitable spring seats formed in the body of the lock cylinder, also not shown.

When the key is not in position to retract the tumblers to their inoperative positions in which their ends lie inwardly of the periphery of the cylinder, their operative end portions 9 are projected beyond the peripheral surface of the cylinder as illustrated in Figure 1.

The projection of the end portions 9 is limited by the engagement of a part of the tumblers With stop means carrier by the lock cylinder as is customary.

Each tumbler has a key opening 10 through which the key (not shown) projects, and the bottom key engaging surface 11 of each opening 19 is so located with respect to the opposite ends of the tumblers as to have a definite predetermined relationship to the particular portion of the key which engages it. Hence, when the key is completely inserted, all of the tumblers will be retracted.

Where the tumblers are fitted to the key by trimming their projecting ends with the key in position, all of the key openings 10 are of the same size, but there is no definite relationship between the positions of the openings 10 with respect to the ends of the Various tumblers. In other words, the surfaces 11 are not placed at one of a few fixed steps, but are indiscriminately located, as determined entirely by the contour of the key. This makes is impossible to decode a lock of this nature with the methods heretofore practiced, and the only possible manner in which it can be decoded is by measuring the position of the surfaces 11 with respect to the bottom of the tumbler groove in the lock easing into which the operative tumbler ends 9 project.

In the present lock, the tumbler groove 12 of the casing 13 in which the cylinder 5 is received, has its bottom 14 of varying depth so that the tumbler ends 9 project beyond the surface of the cylinder diiferent distances as best illustrated in Figure 3, when the lock is in its locked position. Hence, there is no fixed or ascertainable surface from which the location of the surfaces 11 on the tumblers can be measured.

The wave-like formation of the bottom 14 of the tumbler groove may be formed by the core of the die-casting mold, or if desired, the groove may be cored out with a flat bottom as illustrated in Figure 4 and the desired uneven surface produced by an insert 15. The insert 15 may be retained in position in any desired manner as by having a dovetailed engagement in the casing groove.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art to which this invention appertains, that this invention affords novel means for positively precluding the decoding of a tumbler lock and that the provision of this means is accomplished without increasing the cost of the lock and without in any way complicating its design or manufacture.

What I claim as my invention:

1. In a lock comprising a casing and a lock cylinder received therein, a plurality of tumblers carried by the lock cylinder and projectable into a groove in the casing to secure the lock cylinder against rotation, the groove receiving the full width of the tumbler ends and having means to engage the extremities of the tumblers to hold them at different positions with respect to the cylindrical surface of the lock cylinder.

2. In a lock comprising a bored casing and a lock cylinder inserted therein, locking tumblers carried by the lock cylinder and yieldably urged to project one end portion beyond the cylindrical surface of the lock cylinder and into a groove in the casing to secure the lock cylinder against rotation, and a solid uneven wall surface carried by the casing and with which the locking tumblers engage to limit the projection of the locking tumblers to different distances from the cylindrical surface of the lock cylinder.

3. In a lock including a bore casing and a lock cylinder mounted in the casing bore, a plurality of locking tumblers carried by the cylinder and yieldably urged to project one end from the cylinder and into engagement with a groove in the casing to secure the cylinder against movement in the casing bore, the bottom of the groove with which the ends of the tumblers engage being uneven and of varying depth so that the tumbler project different distances from the lock cylinder.

4. In a lock comprising a bored casing having a tumbler receiving groove communicating with its bore, a lock cylinder mounted in the bore, a plurality of locking tumblers carried by the cylinder and yieldably urged to project one end beyond the cylinder and into the groove to secure the cylinder against movement in the easing bore, and means in the groove with which the ends of the tumblers engage to limit the projection of the tumblers into the groove to different distances.

5. In a look, a bored casing having a longitudinal tumbler receiving groove communicating with its bore, a lock cylinder mounted in the bore, a plurality of locking tumblers carried by the cylinder and yieldably urged to project one 110 end beyond the cylinder and into the groove to lock the cylinder against movement, and an insert carried by the casing and forming the bottom of the groove, said insert having its surface forming the bottom of the groove wave-like 115 and uneven so that the tumblers engaging it project varying distances from the lock cylinder. 

